The 1200 Calorie Myth
Many of us who have dieted in the past have aimed for 1200 daily calories at one point or another. It wasn’t until I took masters level nutrition courses that I realized this is literally the calorie needs of a toddler, not of an adult human!
In an effort to demonstrate demonstrate daily calorie needs, I am going to go over some terms and numbers below- hopefully without overwhelming y'all with math:
We need to start by finding basal metabolic rate, or BMR. Some of us have been told to eat at or below this number, but that is never the case! I read a magazine once that told me BMR is the number of calories I burn if I sit and watch TV all day (which tbh I am guilty of at times), and that to lose weight you need to eat 500 calories below that. This is not true, though, as BMR is literally the bare minimum calories your body needs to just survive.
Resting metabolic rate, or RMR, is your BMR plus the energy your body needs to maintain body heat, digest food, and do other complex things for survival. Therefore, this number is higher than your BMR. For this example let's use a 30 year old woman who is 5'5 and weighs 160 lbs. Her RMR is 1,447 calories. This is essentially how many calories she needs to maintain normal body function, and therefore it would not be recommended that she eat less than this amount. We can already see that her daily energy needs are more than 1200 calories!
The RMR is still not how many calories she burns in a day, though. That number would be Total Daily Energy Expenditure or TDEE. To get this calculation, we add RMR + physical activity + the amount of energy needed to digest and absorb food. This depends on activity level and dietary intake, but lets say our example here eats 2,000 calories a day and burns 500 daily active calories each day based on her apple watch. Her TDEE, or the number of calories she burns each day, is 2,147 calories.
Essentially, the person in this example would need to eat 2,147 calories per day to maintain her current body weight. She could decrease this number to lose weight, but 1200 calories would not be nearly enough!
Resources
Mifflin St Jeor Equation:
RMR (female) = 10 (weight in kg) + 6.25 (height in cm) - 5 (age in years) - 161
RMR (male) = 10 (weight in kg) + 6.25 (height in cm) - 5 (age in years) + 5
Total Daily Energy Expenditure equation:
TDEE= RMR + physical activity + TEF
Online calculator: https://www.leighpeele.com/mifflin-st-jeor-calculator
References
Lagerros, Ylva, (2006). Physical activity from the epidemiological perspective— measurement issues and health effects. retrieved from https://www.researchgate.net/publication/237547296_Physical_activity_from_the_epidemiological_perspective-measurement_issues_and_health_effects
Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, and Koh YO, (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2):241-247.
*Please note that the information in this post is for educational use only. Contact your medical provider before adopting any dietary changes.